Defer/async scripts
Detects render-blocking <script> tags in <head> without defer or async.
Why does this matter?
Scripts without defer or async in the <head> block HTML parsing until they are fully loaded and executed. This delays First Contentful Paint (FCP) and can slow down the page by several seconds.
How to fix it?
Add defer to scripts that can execute after the DOM is loaded. Use async for scripts that are independent of the DOM (e.g. analytics). Move scripts before </body> if not possible.
This check scores from 0 to 100. Below 50 is a fail, 50 to 89 is a warning, 90 or above is good. After each crawl you see the score per page in your report, with a short note on what we found.
Frequently asked questions
Detects render-blocking <script> tags in <head> without defer or async.
Scripts without defer or async in the <head> block HTML parsing until they are fully loaded and executed. This delays First Contentful Paint (FCP) and can slow down the page by several seconds.
Add defer to scripts that can execute after the DOM is loaded. Use async for scripts that are independent of the DOM (e.g. analytics). Move scripts before </body> if not possible.
Example
Copy the code below and adapt the domain name, brand name and content to your situation.
<script src="app.js" defer></script>